Technical Field
[0001] The embodiments discussed herein relate to an apparatus and method for processing
images.
Background Art
[0002] There are some existing techniques that add a two-dimensional code as part of a printed
document to embed some information (e.g., character strings) in coded form. A reading
device captures this two-dimensional code on the printed document and decodes the
read data to reconstruct the original information such as character strings.
[0003] Data encryption may be used to conceal a particular part of image data or text data.
When partially encrypted image data is printed on some medium, the encrypted information
appears in a deformed fashion on the resulting printed medium. To obtain its original
information, a reading device is used to capture and decode the encrypted part of
the printed medium. Such data encryption is applied to, for example, a confidential
portion of documents to reduce the risk of information leakage via printed media.
[0004] Some of the existing devices for reading two-dimensional codes and encrypted part
(hereafter "coded portion") are designed to identify which area to decode on the basis
of markers located at four corners (or some of them) of a two-dimensional code or
coded portion.
Citation List
Patent Literature
[0005]
PTL1: Japanese Laid-open Patent Publication No. 07-254037
PTL2: Japanese Laid-open Patent Publication No. 2008-301044
PTL3: Japanese Laid-open Patent Publication No. 2009-232233
Summary of Invention
Technical Problem
[0006] There may be a need for printing a plurality of coded portions on a single medium.
This need arises when, for example, confidential information is distributed in two
or more sections of a document. In the case where those coded portions are closely
located, the markers to be attached to one coded portion could overlap with other
coded portions or other existing markers. Such overlaps would cause a reading device
to fail in reconstructing the information for the following reasons: (1) unable to
detect markers because of their mutual overlaps, or (2) unable to distinguish individual
coded portions because markers are combined incorrectly.
[0007] In view of the foregoing, it is an object of the present invention to provide an
image processing apparatus and method capable of placing markers properly to demarcate
image areas to be processed.
Solution to Problem
[0008] To solve the above problems, there is provided an image processing apparatus. This
image processing apparatus includes an area designation unit, an image processing
unit, a marker area detection unit, and a marking unit. The area designation unit
is configured to designate a processing area within an input image. The image processing
unit is configured to perform predetermined processing on the processing area. The
marker area detection unit is configured to detect an area in the input image which
is capable of accommodating a marker that demarcates the processing area (hereafter,
this area is referred to as a "marker area"). The marking unit is configured to determine
a position in the marker area for placing the marker, based on priority conditions.
[0009] Also, to solve the above problems, there is provided an image processing method including
a procedure similar to what the above image processing apparatus performs.
[0010] Further, to solve the above problems, there is provided another image processing
apparatus. This image processing apparatus includes a marker detection unit, a process
area detection unit, and an image processing unit. The marker detection unit is configured
to detect a plurality of markers in an input image containing a processed area that
has undergone first image processing. The processed area detection unit is configured
to detect position information embedded in the processed area, and detect the processed
area based on the detected position data and control data stored in a control data
storage unit. Here the control data defines, for each possible value of position information,
locational relationships between the markers and a predetermined area. The image processing
unit is configured to perform second image processing on the process area detected
by the process area detection unit.
[0011] Moreover, to solve the above problems, there is provided yet another image processing
apparatus. This image processing apparatus includes a marker detection unit, a process
area detection unit, and an image processing unit. The marker detection unit is configured
to detect a plurality of markers and reference markers in an input image containing
a processed area that has undergone first image processing, the reference markers
being placed within the processed area. The processed area detection unit is configured
to detect locational relationships between the markers and reference markers, and
detect the processed area based on the detected locational relationships and control
data stored in a control data storage unit. Here the control data defines, for each
possible locational relationship, relative positions of the markers with respect to
a predetermined area. The image processing unit is configured to perform second image
processing on the processed area detected by the process area detection unit.
Advantageous Effects of Invention
[0012] The above-noted image processing apparatus and method make it possible to add markers
to an image to properly indicate which part of the image to process.
[0013] The above and other objects, features and advantages of the present invention will
become apparent from the following description when taken in conjunction with the
accompanying drawings which illustrate preferred embodiments of the present invention
by way of example.
Brief Description of Drawings
[0014]
[FIG. 1] FIG. 1 illustrates an image processing apparatus according to a first embodiment.
[FIG. 2] FIG. 2 illustrates an information processing system according to a second
embodiment.
[FIG. 3] FIG. 3 illustrates a hardware configuration of an image processing apparatus
according to the second embodiment.
[FIG. 4] FIG. 4 is a first diagram illustrating a functional structure of the image
processing apparatus according to the second embodiment.
[FIG. 5] FIG. 5 is a second diagram illustrating a functional structure of the image
processing apparatus according to the second embodiment.
[FIG. 6] FIG. 6 illustrates images including encryption areas or encrypted areas.
[FIG. 7] FIG. 7 illustrates markers and search areas.
[FIG. 8] FIG. 8 illustrates an exemplary data structure of a priority table.
[FIG. 9] FIG. 9 is a flowchart illustrating an encryption process according to the
second embodiment.
[FIG. 10] FIG. 10 is a flowchart illustrating how marker areas are detected according
to the second embodiment.
[FIG. 11] FIG. 11 illustrates a specific example of the process of detecting marker
areas according to the second embodiment.
[FIG. 12] FIG. 12 is a flowchart illustrating how markers are placed according to
the second embodiment.
[FIG. 13] FIG. 13 illustrates how reference markers are added.
[FIG. 14] FIG. 14 gives another example of how reference markers are added.
[FIG. 15] FIG. 15 is a first diagram illustrating how markers are placed according
to the second embodiment.
[FIG. 16] FIG. 16 is a second diagram illustrating how markers are placed according
to the second embodiment.
[FIG. 17] FIG. 17 is a third diagram illustrating how markers are placed according
to the second embodiment.
[FIG. 18] FIG. 18 is a flowchart of a decryption process.
[FIG. 19] FIG. 19 is a flowchart illustrating a process of identifying encrypted areas.
[FIG. 20] FIG. 20 is a flowchart illustrating a variation of the process of identifying
encrypted areas.
[FIG. 21] FIG. 21 illustrates a first variation of markers and marker areas.
[FIG. 22] FIG. 22 illustrates a second variation of markers and marker areas.
[FIG. 23] FIG. 23 illustrates a structure of an image processing apparatus according
to a third embodiment.
[FIG. 24] FIG. 24 is a flowchart illustrating an encryption process according to the
third embodiment.
[FIG. 25] FIG. 25 is a flowchart illustrating how adjoining markers are changed according
to the third embodiment.
[FIG. 26] FIG. 26 illustrates how markers are placed according to the third embodiment.
[FIG. 27] FIG. 27 also illustrates how markers are placed according to the third embodiment.
[FIG. 28] FIG. 28 illustrates a structure of an image processing apparatus according
to a fourth embodiment.
[FIG. 29] FIG. 29 illustrates markers used for combining operation of the fourth embodiment.
[FIG. 30] FIG. 30 illustrates a locational relationship between an existing marker
and a search area according to the fourth embodiment.
[FIG. 31] FIG. 31 is a flowchart illustrating an encryption process according to the
fourth embodiment.
[FIG. 32] FIG. 32 is a flowchart illustrating a process of determining marker combination
coordinates according to the fourth embodiment.
[FIG. 33] FIG. 33 illustrates how markers are placed according to the fourth embodiment.
[FIG. 34] FIG. 34 is a flowchart illustrating a variation of the encryption process
according to the fourth embodiment.
[FIG. 35] FIG. 35 illustrates a variation of the marking process according to the
fourth embodiment.
Description of Embodiments
[0015] Several embodiments of the present invention will be described in detail below with
reference to the accompanying drawings.
[First Embodiment]
[0016] FIG. 1 illustrates an image processing apparatus according to a first embodiment.
The illustrated image processing apparatus 1 includes an area designation unit 1a,
an image processing unit 1b, a marker area detection unit 1c, and a marking unit 1d.
[0017] The area designation unit 1a designates a processing area 4 within an input image
2. For example, the area designation unit 1a may receive a user input that specifies
a particular area in the input image 2. The area designation unit 1a designates this
area as a processing area 4. The area designation unit 1a may also be configured to
designate a processing area 4 that has been determined previously.
[0018] The image processing unit 1b performs predetermined image processing on the processing
area 4 designated by the area designation unit 1a. The image processing may include,
for example, encrypting image data, adding two-dimensional codes, and encoding image
data with a compression ratio that is different from those applied to other areas
of the image.
[0019] The marker area detection unit 1c detects a marker area 5 in the input image 2. This
marker area 5 is an area capable of accommodating a marker 6 to demarcate the processing
area 4 when printed on some medium as part of an output image. The marker 6 is a piece
of image to be placed on the periphery of the processing area 4, in order to help
a reading device to identify the processing area 4 in the printed output image. The
marker 6 may have various shapes. For example, an L-shaped marker may be placed at
each of the four corners of the processing area 4, with its pixel values arranged
in a predetermined pattern. Other exemplary markers may take a round shape or a rectangular
shape having a predetermined pixel pattern, similarly placed at each corner of the
processing area 4.
[0020] The marker area detection unit 1c detects a marker area 5 from, for example, inside
the processing area 4, as well as from the periphery of the same. For example, there
are several potential areas for placement of markers, and they are previously defined
depending on the shape of markers. The marker area detection unit 1c excludes some
positions in those areas as being unsuitable for markers 6 when these positions overlap
with (1) other processing areas than the processing area 4 of interest, or (2) other
makers demarcating processing areas other than the processing area 4 of interest.
That is, the marker area detection unit 1c detects a marker area 5 by removing the
positions that satisfy the condition (1) or (2).
[0021] The marking unit 1d determines where in the marker area 5 to place a marker 6, on
the basis of a set of priority conditions. The priority conditions may be previously
specified. For example, a marker position is given a higher priority when it does
not overlap with the processing area 4. The marking unit 1d has been configured with
such predetermined priority conditions. Based on the above determination, the marking
unit 1d places a marker 6 in the image processed by the image processing unit 1b,
thus producing an output image 3.
[0022] In operation of the above image processing apparatus 1, the area designation unit
1a designates a processing area 4 in an input image 2 that is received. The image
processing unit 1b performs predetermined image processing on the designated processing
area 4. The marker area detection unit 1c detects a marker area 5 capable of accommodating
a marker 6 to demarcate the processing area 4. The marking unit 1d determines where
in the marker area 5 to place a marker 6 on the basis of a predetermined set of priority
conditions.
[0023] As a result of the above operation, markers are placed properly to demarcate a processing
area 4 to be encoded. For example, markers 6 can be located in an appropriate place
not overlapping with other processing areas. When the resulting output image 3 is
printed on a medium, these markers 6 help a reading device to capture the data on
the printed medium.
[0024] The input image 2 may include a plurality of processing areas. It has conventionally
been unavoidable in such a case to separate those processing areas with sufficient
distances, so that a reading device can recognize their markers properly. In contrast,
the method proposed above makes it possible to lay out such processing areas closely
together, and it thus reduces the space for arranging, for example, a plurality of
two-dimensional codes, besides allowing encryption of those adjoining areas.
[0025] More specific embodiments of the above image processing apparatus 1 will be discussed
below. These embodiments assume that their proposed techniques are applied to an information
processing system that protects printed media from information leakage.
[Second Embodiment]
[0026] FIG. 2 illustrates an information processing system according to a second embodiment.
This information processing system includes a printer 20, a scanner 30, and image
processing apparatuses 100 and 200 connected via a network 10.
[0027] The network 10 may be an intranet or the Internet.
[0028] The printer 20 is an output device for producing printed media X1.
[0029] The scanner 30 is an input device for capturing image data printed on a printed medium
X1.
[0030] The image processing apparatuses 100 and 200 are computers configured to process
image data. Specifically, these image processing apparatuses 100 and 200 cause the
printer 20 to print image data. The image processing apparatuses 100 and 200 receive
image data captured by the scanner 30. The image processing apparatuses 100 and 200
encrypt a part of the received image data.
[0031] The original information contained in an encrypted portion does not appear in comprehensible
form on a printed medium X1. Thus it is not possible for a third party to reach the
content even if the printed medium X1 is accessible to them. In other words, leakage
of information through such printed media X1 is less likely.
[0032] The following description assumes that one image processing apparatus 100 encrypts
a part of given image data and the other image processing apparatus 200 decrypts that
part of the image data. While they play different roles, the former image processing
apparatus 100 may include the same functions as the latter image processing apparatus
200. Similarly the latter image processing apparatus 200 may include the same functions
as the former image processing apparatus 100.
[0033] FIG. 3 illustrates a hardware configuration of an image processing apparatus according
to the second embodiment. This image processing apparatus 100 includes a central processing
unit (CPU) 101, a read-only memory (ROM) 102, a random access memory (RAM) 103, a
hard disk drive (HDD) 104, a graphics processor 105, an input device interface 106,
a storage media drive 107, and a communication interface 108.
[0034] The CPU 101 controls the image processing apparatus 100 as a whole.
[0035] The ROM 102 stores, for example, a basic input/output system (BIOS) program of the
image processing apparatus 100.
[0036] The RAM 103 serves as temporary storage for at least part of operating system (OS)
programs and application software (hereafter "applications") that the CPU 101 executes,
as well as for various data that the CPU 101 uses when executing the programs.
[0037] The HDD 104 stores OS programs and application programs. The HDD 104 also stores
various data that the CPU 101 needs for its processing operation. Solid state drives
(SSD) or other type of storage devices may be used in place of, or together with the
HDD 104.
[0038] The graphics processor 105, coupled to a monitor 11, produces video images in accordance
with drawing commands from the CPU 101 and displays them on a screen of the monitor
11.
[0039] The input device interface 106 is connected to a keyboard 12 and a mouse 13 and supplies
signals from those devices to the CPU 101.
[0040] The storage media drive 107 is a device used to read data in a storage medium 14.
For example, the functions that the image processing apparatus 100 is supposed to
provide may be encoded as computer programs to be run on a computer system. These
programs may be recorded on a computer-readable storage medium 14 for the purpose
of distribution. The programs may also be stored in a program distribution server
(not illustrated) which is linked to a network 10. In this case, the image processing
apparatus 100 can download programs from the program distribution server via the network
10.
[0041] The storage medium 14 may be, for example, a magnetic storage device, optical disc,
magneto-optical storage medium, or semiconductor memory device. Magnetic storage devices
include hard disk drives (HDD), flexible disks (FD), and magnetic tapes, for example.
Optical discs include, for example, compact disc (CD), CD-Recordable (CD-R), CD-Rewritable
(CD-RW), digital versatile disc (DVD), DVD-R, DVD-RW, and DVD-RAM. Magneto-optical
storage media include magneto-optical discs (MO), for example. Semiconductor memory
devices include, for example, flash memory devices such as Universal Serial Bus (USB)
flash drives.
[0042] The communication interface 108 is connected to the network 10 to exchange data with
a printer 20, scanner 30, and other information processing apparatuses.
[0043] The above hardware configuration of the image processing apparatus 100 may also be
used to realize the other image processing apparatus 200.
[0044] FIG. 4 is a first diagram illustrating a functional structure of the image processing
apparatus according to the second embodiment. The illustrated image processing apparatus
100 includes a control data storage unit 110, an encryption area designation unit
120, an encryption unit 130, a marker area detection unit 140, and a marking unit
150. These functions are realized as programs executed by the CPU 101. Alternatively,
all or part of those functions may be implemented as a dedicated hardware device(s).
[0045] The control data storage unit 110 stores control data used to determine the position
of markers for locating an encryption area. The control data includes the following
information:
(A1) Information describing search areas in which it is determined whether a marker
can be placed or not, depending on the shape of markers.
(A2) Information describing priority conditions used to determine the position of
markers, within a marker area extracted as part of a search area as being capable
of accommodating markers.
(A3) Information indicating the positions of other existing encryption areas in the
same image and their respective markers.
[0046] The encryption area designation unit 120 receives an input image 300 as source data.
The encryption area designation unit 120 also receives a user input designating which
areas in the input image 300 to protect with encryption. The encryption area designation
unit 120 informs the encryption unit 130 and marker area detection unit 140 of these
areas (hereafter "designated areas").
[0047] The encryption area designation unit 120 stores the received input image 300 in an
area of RAM 103, for example. The encryption area designation unit 120, encryption
unit 130, marker area detection unit 140 and marking unit 150 perform various operations
(described below) on the input image 300 by manipulating the stored data in the RAM
103.
[0048] The encryption unit 130 encrypts each designated area of the input image 300 by using
a predetermined cryptographic key. The cryptographic key may previously be given to
and held by the encryption unit 130. Alternatively, the user may be prompted to enter
a key phrase for use as the cryptographic key for encryption.
[0049] The marker area detection unit 140 determines a marker area for each designated area
informed of by the encryption area designation unit 120, based on the control data
stored in the control data storage unit 110. Some areas may overlap with other encryption
areas or their markers. The marker area detection unit 140 does not select such areas
as marker areas. The marker area detection unit 140 outputs determined marker areas
to the marking unit 150.
[0050] From among these marker areas supplied from the marker area detection unit 140, the
marking unit 150 determines positions for placing markers in the input image 300 encrypted
by the encryption unit 130, based on the above control data in the control data storage
unit 110. The marking unit 150 places a marker at each determined position, thus producing
and outputting an encrypted image 300a.
[0051] The image processing apparatus 100 accepts a print command from the user and causes
the printer 20 to print the encrypted image 300a accordingly. The resulting printed
medium X1 includes the encrypted image 300a.
[0052] To browse an encrypted part of the printed media X1, the user causes his or her image
processing apparatus 200 to decrypt the encrypted image 300a. To this end, the user
operates a scanner 30 to read out what is recorded on the printed media X1. The scanner
30 captures the encrypted image 300a, and supplies the image processing apparatus
200 with the captured image. An alternative method for capturing such an encrypted
image 300a on printed media X1 is to use a digital still camera or an integrated camera
function of a cellular phone, PC, or other information technology device.
[0053] FIG. 5 is a second diagram illustrating a functional structure of the image processing
apparatus according to the second embodiment. The illustrated image processing apparatus
200 includes a decryption control data storage unit 210, a marker position detection
unit 220, an encrypted area detection unit 230, and a decryption unit 240. These functions
are realized as programs executed by a CPU in the image processing apparatus 200.
Alternatively, all or part of these functions may be implemented as a dedicated hardware
device(s).
[0054] The decryption control data storage unit 210 stores data used to detect markers for
locating an encrypted area. This decryption control data may include the following
information:
(B1) Information for determining priority conditions from marker positions (this information
corresponds to what has previously been described as control data (A2) stored in the
control data storage unit 110).
(B2) Information defining the shape and color pattern of markers to be placed by the
image processing apparatus 100.
[0055] The marker position detection unit 220 is responsive to input of an encrypted image
300a. In response, the marker position detection unit 220 detects the position of
each marker by searching the encrypted image 300a for a predetermined pattern, using
pattern matching or other generally known techniques. The marker position detection
unit 220 informs the encrypted area detection unit 230 of the detected marker positions.
[0056] The marker position detection unit 220 stores data of the encrypted image 300a in
a predetermined area of RAM in the image processing apparatus 200. The marker position
detection unit 220, encrypted area detection unit 230, and decryption unit 240 perform
their respective processing functions (described below) on the encrypted image 300a
by manipulating this data in the RAM area.
[0057] The encrypted area detection unit 230 detects encrypted areas in the encrypted image
300a, based on marker positions detected by the marker position detection unit 220,
as well as on decryption control data stored in the decryption control data storage
unit 210. The encrypted area detection unit 230 informs the decryption unit 240 of
the detected encrypted areas.
[0058] The decryption unit 240 decrypts an encrypted area in the encrypted image 300a by
using a predetermined cryptographic key. The cryptographic key for this purpose may
previously be provided to the decryption unit 240. Alternatively, the user may be
prompted to enter a key phrase for use as the cryptographic key for decryption. The
decryption unit 240 produces and outputs a decrypted image 300b as a result of its
decryption processing.
[0059] The image processing apparatus 200 outputs the decrypted image 300b on, for example,
a monitor coupled to the image processing apparatus 200. This display on the monitor
screen permits the user to browse information in encrypted areas of the printed medium
X1.
[0060] FIG. 6 illustrates images including encryption areas or encrypted areas. Section
(A) of FIG. 6 illustrates an example of an input image 300. Section (B) of the same
illustrates an example of an encrypted image 300a.
[0061] The encryption area designation unit 120 permits the user to designate some particular
areas in the input image 300. For example, the input image 300 may include such designated
areas 310 and 320. The user designates these areas 310 and 320 by manipulating a mouse
13 and dragging pointer P1 in the input image 300 seen on the monitor 11, so that
each area 310 and 320 can be selected.
[0062] The user may further enter an input command to the image processing apparatus 200
to initiate encryption of data. For example, some buttons may be displayed together
with the input image 300 on the monitor 11, to allow the user to enter such input
commands.
[0063] Upon receipt of a user input initiating encryption, the encryption area designation
unit 120 triggers encryption of two designated areas 310 and 320 in the order that
they are specified. Alternatively, the encryption area designation unit 120 triggers
encryption of those designated areas 310 and 320 in ascending order of their coordinate
values (e.g., y-axis values) within the input image 300. When the first-specified
area is finished, the encryption area designation unit 120 subjects the next designated
area to encryption processing. Suppose, for example, that the user has specified one
designated area 310 in the first place. The encryption area designation unit 120 encrypts
the designated area 310 and places markers therefor, thus producing an encrypted area
310a. The encryption area designation unit 120 then proceeds to the other designated
area 320 and similarly initiates encryption and marker placement, thus producing another
encrypted area 320a. Two encrypted areas 310a and 320a are produced in this way, by
subjecting every designated area 310 and 320 to the encryption process. The resulting
image, including encrypted areas 310a and 320a, is referred to as an encrypted image
300a.
[0064] The above description has exemplified the case of two designated areas. The same
description may similarly apply to the cases in which there are three or more designated
areas.
[0065] FIG. 7 illustrates markers and search areas. Section (A) of FIG. 7 illustrates the
shape and pixel pattern of markers, while section (B) of the same illustrates search
areas corresponding to the markers.
[0066] Specifically, markers M1, M2, M3, and M4 are placed at four corners of an encrypted
area 320a, each having an L-shaped figure with a specific pixel pattern. The pixel
pattern may be composed as, for example, a repetitive series of white and black pixel
blocks each constituted by one or more pixels. While the following description assumes
that marker patterns are each composed of white and black blocks, the embodiments
should not be limited by this specific setup, and other patterns may also be applicable
as long as they distinguish from each other. For example, some marker patterns may
use some distinguishable color components such as red and blue. In the illustrated
pattern of FIG. 7, white blocks and black blocks are concatenated alternately. Variations
of this pattern may take other arrangements such as white-white-black-white-white-black,
or white-black-black-white-black-black. Marker patterns may also vary in size and
proportion. For example, the ratio of horizontal and vertical lengths may be set to
7:7 or 5:7 or any other values, as opposed to the 5-by-5 L-shaped pattern illustrated
in FIG. 7.
[0067] The image processing apparatus 200 can identify the boundaries of the encrypted area
320a by detecting markers M1, M2, M3, and M4.
[0068] Search areas Q1, Q2, Q3, and Q4 are where markers M1, M2, M3, M4 may be placed in
relation to a designated area 320. The control data storage unit 110 stores control
data that defines such search areas Q1, Q2, Q3, and Q4 containing four corners of
the designated area 320. This definition may actually depend on the shape of markers
M1, M2, M3, and M4.
[0069] The following description assumes that the image processing apparatus 200 places
the above-described markers M1, M2, M3, and M4. The image processing apparatus 200
may, however, place markers having other shape, as will be described later.
[0070] FIG. 8 illustrates an exemplary data structure of a priority table, which is previously
defined and stored in the control data storage unit 110 and decryption control data
storage unit 210. The illustrated priority table 111 has two data fields respectively
indicating priority and locational relationship. The data values horizontally arranged
in this table are associated with each other to constitute a specific priority condition.
[0071] The priority field contains information indicating a specific priority level. For
example, smaller priority values mean higher priority levels. The locational relationship
field indicates a locational relationship between a marker and an encryption area.
The terms "supper," "lower," "right," and "left" will be used to represent the upward,
downward, rightward, and leftward directions as viewed in FIG. 8.
[0072] For example, the priority table 111 contains a priority of "1" and its associated
locational condition, which says: marker M1 is located at the upper-left corner of
an encrypted area 320a without gaps. The priority table 111 of FIG. 8 represents this
condition in a graphical fashion (the same applies to the rest).
[0073] Another record of the priority table 111 contains a priority of "2" and its associated
locational condition, which says: marker M1 is located half a block lower than the
marker position of priority "1" described above.
[0074] Yet another record of the priority table 111 contains a priority of "3" and its associated
locational condition, which says: marker M1 is located half a block to the right of
the marker position of priority "2" described above.
[0075] Still another record of the priority table 111 contains a priority of "4" and its
associated locational condition, which says: marker M1 is located half a block lower
than the marker position of priority "3" described above.
[0076] Still another record of the priority table 111 contains a priority of "5" and its
associated locational condition, which says: marker M1 is located half a block to
the right of the marker position of priority "4" described above.
[0077] The collection of such potential locations of marker M1 defined in the priority table
111 gives what has been discussed as a search area Q1 in FIG. 7.
[0078] The above-described priority table 111 exemplifies one marker M1. Priorities of other
markers M2, M3, and M4 are also defined in a similar way, but depending on their locations
relative to the encrypted area 320a.
[0079] For example, a priority of "1" is given to the location of markers M2, M3, and M4
when it is a corner of the encrypted area 320a without gaps. A priority of "2" is
given to the marker location that is vertically away from the marker position of priority
"1" described above, half a block toward the inside of the encrypted area 320a. A
priority of "3" is given to the marker location that is horizontally away from the
marker position of priority "2" described above, half a block toward the inside of
the encrypted area 320a. A priority of "4" is given to the marker location that is
vertically away from the marker position of priority "3" described above, half a block
toward the inside of the encrypted area 320a. A priority of "5" is given to the marker
location that is horizontally away from the marker position of priority "4" described
above, half a block toward the inside of the encrypted area 320a.
[0080] As can be seen from the above example, the priority table 111 defines priority of
each possible location of markers. Specifically, a higher priority is given to marker
locations as they have less overlap with the encrypted area 320a.
[0081] The locational relationship field of the priority table 111 may actually contain,
for example, relative coordinates of a reference point of a marker with respect to
that of the encrypted area 320a. More specifically, a marker is composed of two bars
respectively extending in the horizontal and vertical directions. The reference point
of the marker may be defined to be a pixel at the intersection of these two bars,
and more particularly, the reference-point pixel may be the most inward one of the
pixels constituting the intersecting block. The encrypted area 320a, on the other
hand, may have its reference point at a pixel of the corner closest to the marker
in question. For example, when the marker has a line width of four pixels, the relative
coordinates of priority "1" in FIG. 8 are expressed as (1, 1). Similarly the relative
coordinates of priority "3" and priority "5" in FIG. 8 are expressed as (3, 3) and
(5, 5), respectively.
[0082] The above example of locational relationships assumes that markers are placed with
a half-block resolution. Other possible resolutions include one third block, one fourth
block, and other finer fractions. The use of finer units of resolution reduces the
amount of overlap of each marker with the encrypted area 320a.
[0083] According to the above-described locational relationships, the highest priority "1"
is given to the case where the marker M1 and encrypted area 320a are next to each
other. It is also possible, however, to define more locational relationships with
a higher priority. For example, marker M1 may move from its priority-1 location by
some pixels in the upper-left direction, away from the encrypted area 320a, and a
higher priority is then given to the marker M1 in that new position. The marker M1
at this position is apart from the encrypted area 320a, thus preventing their boundaries
from becoming obscure when they are printed.
[0084] The above-described information in the priority table 111 is applied to one search
area Q1. A priority table is similarly defined for each of the other search areas
Q2, Q3, and Q4.
[0085] The next section of this description provides details of processing operation that
the above image processing apparatuses 100 and 200 execute. To start with, an encryption
process of the image processing apparatus 100 will now be described below.
[0086] FIG. 9 is a flowchart illustrating an encryption process according to the second
embodiment. Each step of this process is described below in the order of step numbers.
[0087] (Step S11) The encryption area designation unit 120 receives an input image 300.
[0088] (Step S12) The encryption area designation unit 120 permits the user to designate
a specific area(s) in the input image 300. It is assumed now that the user has designated
two or more areas.
[0089] (Step S13) The encryption area designation unit 120 selects one of the designated
areas. For example, the encryption area designation unit 120 may select these areas
in the order that the user has designated. Alternatively, the encryption area designation
unit 120 may select the areas in ascending order of their coordinates (e.g., y coordinates)
within the input image 300. Suppose, for example, that there are two designated areas
310 and 320. The encryption area designation unit 120 selects the former area 310
in the first place and informs the encryption unit 130 and marker area detection unit
140 of the selected area.
[0090] (Step S14) The encryption unit 130 encrypts the designated area that is informed
of by the encryption area designation unit 120. The encryption unit 130 produces and
stores control data in the control data storage unit 110 to record which part of the
input image 300 is encrypted. For example, this control data may record the corner
points of the encrypted area.
[0091] (Step S15) The marker area detection unit 140 obtains search areas Q1, Q2, Q3, and
Q4 relevant to the designated area informed of by the encryption area designation
unit 120, by consulting the control data stored in the control data storage unit 110.
Out of these search areas Q1, Q2, Q3, and Q4, the marker area detection unit 140 detects
appropriate marker areas by excluding coordinate points that overlap with other encrypted
areas or their markers. The marker area detection unit 140 provides the marking unit
150 with the detected marker areas.
[0092] (Step S16) With reference to a relevant priority table 111 stored in the control
data storage unit 110, the marking unit 150 places a marker at the highest-priority
position in each marker area so as to indicate the encrypted area in the input image
300. The marking unit 150 adds control data to the control data storage unit 110 to
record the marked area (e.g., record each corner positions of the area).
[0093] (Step S17) The marking unit 150 determines whether there is any pending designated
area in the input image 300. If there is, the marking unit 150 moves the process back
to step S13. If all the designated areas are finished, the marking unit 150 outputs
the resulting encrypted image 300a, thus terminating the present process.
[0094] As can be seen from the above steps, the image processing apparatus 100 encrypts
data locally in each designated area. Markers are then placed at each resulting data
area (encrypted area) for the purpose of demarcation.
[0095] The above procedure executes encryption at step S14. Alternatively, the procedure
may be modified to perform the same immediately before the marker placement of step
S16.
[0096] The above step S15 will now be described in detail below.
[0097] FIG. 10 is a flowchart illustrating how marker areas are detected according to the
second embodiment. Each step of this process is described below in the order of step
numbers.
[0098] (Step S21) With reference to control data stored in the control data storage unit
110, the marker area detection unit 140 obtains search areas Q1, Q2, Q3, and Q4 relevant
to the designated area informed of by the encryption area designation unit 120.
[0099] (Step S22) The marker area detection unit 140 selects one of the search areas Q1,
Q2, Q3, and Q4. Suppose, for example, that search area Q1 is selected.
[0100] (Step S23) The marker area detection unit 140 identifies other encrypted areas and
their marker positions. More specifically, the marker area detection unit 140 searches
the control data stored in the control data storage unit 110 to retrieve coordinate
values representing the corner points of existing encrypted areas and existing marker
areas.
[0101] (Step S24) The marker area detection unit 140 takes one pixel contained in the selected
search area and obtains a coordinate point P of that pixel.
[0102] (Step S25) The marker area detection unit 140 determines whether the obtained coordinate
point P lies outside of the other encrypted areas. When P lies outside, the marker
area detection unit 140 advances the process to step S26. When P lies inside, the
marker area detection unit 140 advances the process to step S28.
[0104] (Step S26) The marker area detection unit 140 determines whether the coordinate point
P lies outside the markers of other encrypted areas. When P lies outside, the marker
area detection unit 140 advances the process to step S27. When P lies inside, the
marker area detection unit 140 advances the process to step S28.
[0105] The test of whether the coordinate point P are outside or inside markers is performed
with the same method discussed above in step S25.
[0106] (Step S27) The marker area detection unit 140 adds the coordinate point P to the
marker area.
[0107] (Step S28) The marker area detection unit 140 gives a "finished" status to the coordinate
point P, which are among those contained in the selected search area.
[0108] (Step S29) The marker area detection unit 140 determines whether the selected search
area still contains pending coordinate points. When a pending coordinate point is
found, the marker area detection unit 140 goes back to step S24. When no pending coordinate
points are found, the marker area detection unit 140 outputs the resulting marker
area to the marking unit 150, thus advancing the process to step S30. For example,
the marker area detection unit 140 outputs information indicating a marker area R1
for the search area Q1.
[0109] (Step S30) The marker area detection unit 140 determines whether the search areas
Q1, Q2, Q3, and Q4 include any other pending search areas that have not undergone
the above search. When there are pending search areas, the marker area detection unit
140 goes back to step S22. When all the search areas have undergone the above search,
the marker area detection unit 140 terminates the process.
[0110] As can be seen from the above description, the marker area detection unit 140 scans
each search area Q1, Q2, Q3, and Q4 to extract coordinate points that do not overlap
with other encrypted areas or their markers. The resulting set of coordinate points
forms a marker area.
[0111] FIG. 11 illustrates a specific example of the process of detecting marker areas according
to the second embodiment. Section (A) of FIG. 11 illustrates an exemplary arrangement
of an encrypted area 310a, its associated markers, and a designated area 320. Section
(B) depicts exemplary marker areas that marker area detection unit 140 detects under
the arrangement of (A). It is noted here that one designated area 310 has been encrypted
before another designated area 320, and thus there exists an encrypted area 310a.
[0112] When the encrypted area 310a is close to the designated area 320, the encrypted area
310a and its markers may partly overlap with search areas Q1, Q2, Q3, and Q4. If this
is the case, the marker area detection unit 140 collects appropriate coordinate points
in each search area Q1, Q2, Q3, and Q4 which do not overlap with the encrypted area
310a or its associated markers. The resulting sets of coordinate points constitute
marker areas R1, R2, R3, and R4. Referring to the example of FIG. 11, the first two
marker areas R1 and R2 are created from the search areas Q1 and Q2 in FIG. 7 by removing
their respective overlaps with some markers for the encrypted area 310a. The marking
unit 150 uses such marker areas R1, R2, R3, and R4 to select appropriate places for
markers M1, M2, M3, and M4, not to make them overlap with the encrypted area 310a
and its associated markers.
[0113] The foregoing step S16 of FIG. 9 will now be described in detail below.
[0114] FIG. 12 is a flowchart illustrating how markers are placed according to the second
embodiment. Each step of this process is described below in the order of step numbers.
[0115] (Step S31) The marking unit 150 selects a marker area. Specifically, the marking
unit 150 selects one of the marker areas R1, R2, R3, and R4 detected by the marker
area detection unit 140. Suppose, for example, that one marker area R1 is selected.
[0116] (Step S32) The marking unit 150 consults a relevant priority table 111 in the control
data storage unit 110 to find a marker position with the highest priority. Specifically,
this marker position has a priority of "1" in the priority table 111. As mentioned
previously, the priority of marker positions is defined separately for each search
area Q1, Q2, Q3, and Q4. In the case of marker area R1, the marking unit 150 consults
the foregoing priority table 111 since this table contains information about search
area Q1 corresponding to the marker area R1 in question.
[0117] (Step S33) The marking unit 150 tries to place a marker in the selected marker area.
That is, the marking unit 150 determines whether it is possible to place a marker
at the marker position with the current priority. If a marker is not placeable, the
marking unit 150 advances the process to step S34. If it is placeable, the marking
unit 150 advances the process to step S37.
[0118] More specifically, the word "placeable" is used to mean that the marker area can
contain a marker in its entirety. When the marker extends off the marker area, it
is not placeable. Referring to, for example, the marker area R1 detected as in section
(B) of FIG. 11, it is not possible to place a marker M1 at the position with a priority
of "1" in FIG. 8. The same marker area R1 can, however, accommodate a marker M1 when
it is placed at the position with a priority of "2" in FIG. 8. As to another marker
area R3 seen in section (B) of FIG. 11, a marker M3 is placeable in that area even
at the position of priority "1."
[0119] (Step S34) With reference again to the priority table 111, the marking unit 150 determines
whether there is a priority lower than the currently selected one. When no lower priority
is found, the marking unit 150 advances the process to step S35. When there is a lower
priority, the marking unit 150 advances the process to step S36.
[0120] (Step S35) The marking unit 150 invokes an error handling routine. For example, the
marking unit 150 causes a message to appear on the monitor 11 to inform the user that
markers are not placeable. The process of FIG. 12 is thus terminated.
[0121] (Step S36) From among those in the priority table 111, the marking unit 150 selects
a new priority that is lower than the currently selected one. For example, the marking
unit 150 selects priority "2" when the current priority is "1" and then advances the
process to step S33.
[0122] (Step S37) The marking unit 150 places a marker at the position corresponding to
the current priority. The marking unit 150 gives a "finished" status to the currently
selected marker area.
[0123] When placing a marker, the marking unit 150 does some additional work to indicate
which priority was used for that marker. This is for the purpose of later distinction
when the image is read. For example, the marking unit 150 may add a reference marker(s)
at some specific point(s) in relation to the newly placed marker. A specific example
will be discussed in a later section.
[0124] (Step S38) The marking unit 150 determines whether there are any other pending marker
areas. When a pending marker area is found, the marking unit 150 goes back to step
S31. When all marker areas are finished, it means the end of the process of FIG. 12.
Marker areas may be selected in any desired order. For example, the marking unit 150
selects four marker areas R1, R2, R3, and R4 in that order.
[0125] The above-described steps permit the marking unit 150 to find an appropriate marker
position with as high a priority as possible, so that a maker M1 can be placed within
a marker area R1. It is therefore possible to add markers to a new encryption area
without overlap with exiting encrypted areas and their associated markers, as well
as minimizing the amount of overlap with the new encryption area.
[0126] The next section will describe a more specific example of marker placement performed
by the marking unit 150 at step S37. Described in the first place is a marker placement
method that enables readout of data together with information indicating the priority
of marker positions.
[0127] FIG. 13 illustrates how reference markers are added. Here the marking unit 150 adds
reference markers M5, M6, M7, and M8 in relation to a marker M1. Section (A) of FIG.
13 illustrates the case of priority "1,"' while section (B) illustrates the case of
priority "5."
[0128] Specifically, the marking unit 150 sets a reference point at the position that is
horizontally away from one corner (e.g., upper-left corner in FIG. 13) of an encrypted
area 320a by a predetermined distance in the direction toward inside of the encrypted
area 320a (in the rightward direction in FIG. 13). Then the marking unit 150 adds
two reference markers M5 and M6 in such a way that one of them (e.g., reference marker
M5) will be right on the reference point.
[0129] The marking unit 150 sets another reference point at the position that is vertically
away from the corner of the encrypted area 320a (e.g., upper-left corner in FIG. 13)
by a predetermined distance in the direction toward inside of the encrypted area 320a
(in the downward direction in FIG. 13). Then the marking unit 150 adds another two
reference markers M7 and M8 in such a way that one of them (e.g., reference marker
M7) will be right on the reference point.
[0130] In the way described above, the marking unit 150 puts reference markers M5, M6, M7,
and M8 at predetermined places in the encrypted area 320a. While FIG. 13 illustrates
black dots as an example, the reference markers M5, M6, M7, and M8 may take other
form such as white dots. As another implementation, some pixels inside the encrypted
area 320a may be reversed or shifted to constitute reference markers. A reading device
locates the marker M1 and reference markers M5, M6, M7, and M8 when capturing the
image. Here the locational relationships between the marker M1 and reference markers
M5, M6, M7, and M8 indicate which priority was used to position the marker M1.
[0131] For example, the image processing apparatus 200 scans a plurality of rows on a given
encrypted image 300a, including those of markers M1, thereby detecting reference markers
M5 and M6. One of these reference markers M5 and M6 sits on the reference point. It
is the former reference marker M5 in the present case. The image processing apparatus
200 then evaluates the locational relationship (or distance) between the reference
marker M5 and marker M1 in the vertical or horizontal direction. Likewise, the image
processing apparatus 200 also manipulates a plurality of columns on the encrypted
image 300a, including those of markers M1, thereby detecting another two reference
markers M7 and M8. One of these reference markers M7 and M8 sits on the reference
point. It is the former reference marker M7 in the present case. The image processing
apparatus 200 then evaluates a locational relationship (or distance) between the reference
marker M7 and marker M1 in the vertical or horizontal direction. In this way, the
image processing apparatus 200 detects locational relationships between the marker
M1 and each reference marker.
[0132] The priority of marker M1 is associated with the marker's locational relationships
with reference markers M5, M6, M7, and M8. This association between the priority and
locational relationships is previously agreed upon by the two image processing apparatuses
100 and 200 and stored as part of the decryption control data in the decryption control
data storage unit 210. Reference markers M5, M6, M7, and M8 have specific colors,
spaces, and indication of a reference point. This arrangement pattern of reference
markers is previously defined and stored as part of control data in the control data
storage unit 110, also as decryption control data in the decryption control data storage
unit 210.
[0133] With reference to such control data, the image processing apparatus 200 identifies
which priority the image processing apparatus 100 used to place the marker M1 in question,
based on its location relative to the reference markers M5, M6, M7, and M8.
[0134] In the above example, each marker has a plurality of reference markers. The embodiments
are, however, not limited by that specific example. Alternatively, reference markers
may be placed at the middle point of each edge of an encrypted area 320a, so that
two markers at adjacent corners share their reference markers. For example, reference
markers M5 and M6 may be configured to serve two markers M1 and M2, so that these
reference markers can also be used to identify the priority of marker M2. Similarly,
reference markers M7 and M8 may be configured to serve two markers M1 and M3, so that
these reference markers can also be used to identify the priority of marker M3.
[0135] In the above example, two pairs of reference markers are provided for one marker,
one pair being horizontally aligned with the marker, the other pair being vertically
aligned with the marker. The embodiments are, again, not limited by that specific
implementation. For example, three or more reference markers may be placed in each
of the horizontal and vertical directions.
[0136] It would also be possible to vary the pixel pattern of new markers in accordance
with their respective priorities, so that the priority of a marker can be recognized
from its pixel pattern. The following section describes this variation of the embodiment.
[0137] FIG. 14 gives another example of how reference markers are added. The marking unit
150 changes the pixel pattern of each block constituting markers, depending on their
priorities. Such pixel patterns of markers substantially indicate relative positions
of the markers with respect to their associated encrypted area. Section (A) of FIG.
14 illustrates the case of priority "1," while section (B) illustrates the case of
priority "5."
[0138] Variations of pixel pattern may be achieved by, for example, changing the order of
white blocks and black blocks. Another example is to vary the intervals of alternating
white and black blocks. In the example of FIG. 14, the pixel pattern of marker M1f
at the priority-5 position is in reverse order to that of marker M1e at the priority-1
position.
[0139] The association between pixel pattern and priority is previously agreed upon by the
two image processing apparatuses 100 and 200 and stored as part of control data in
the control data storage unit 110. The association is also stored as part of decryption
control data in the decryption control data storage unit 210.
[0140] Such control data permits the image processing apparatus 200 to identify which priority
the image processing apparatus 100 used to place the marker M1.
[0141] The information indicating priority may be embedded at a position that overlaps with
markers, or at a position that does not overlap with markers. The pixel pattern of
reference markers illustrated in FIG. 13 may be changed depending on the priority,
so that the priority of marker M1 can be identified at the decoding end.
[0142] A more specific example of marker placement will now be explained below.
[0143] FIG. 15 is a first diagram illustrating how markers are placed according to the second
embodiment. Section (A) of FIG. 15 illustrates a marker M1 overlapping with its associated
encrypted area 320a. Section (B) of FIG. 15, on the other hand, illustrates the case
where the image processing apparatus 100 places a marker M1 after shrinking an area
321a to avoid their overlap.
[0144] More specifically, section (A) of FIG. 15 illustrates the case where the image processing
apparatus 100 has performed a process of encryption and marker placement in the way
described below. First, at step S37 of FIG. 12, the marking unit 150 places a marker
in an area where the marker partly overlaps with an encryption area. This overlap
causes a partial loss of data in the encryption area.
[0145] The image processing apparatus 200 reads out image data in the encrypted area 320a
while recovering information in the above-noted overlap with the marker M1 by using
interpolation or extrapolation techniques. The image processing apparatus 200 decrypts
the encrypted area 320a based on its recovered image data.
[0146] There is an alternative method to deal with such overlap of an encrypted area 320a
and markers. That is, markers may be placed in the way illustrated in section (B)
of FIG. 15.
[0147] At step S37 of FIG. 12, the marking unit 150 divides the encrypted area 320a into
four areas 321a, 322a, 323a, and 324a and scales down one area 321a since it partly
overlaps with marker. Before a marker M1 is placed, the shrunken image of the area
321a is moved to another area 321b that has no overlap with the marker M1. The shrink
ratio may be determined according to the priority. For example, the shrink ratio is
determined such that one corner of the shrunken area 321b will be immediately adjacent
to its opposite corner of the marker M1.
[0148] While alphabets A, B, C, and D are seen in the areas 321a, 321b, 322a, 323a, and
324a of FIG. 15, these letters are used only for the purpose of making these areas
distinguishable.
[0149] The image processing apparatus 200 reads the image seen in section (B) of FIG. 15.
Here the image processing apparatus 200 expands the shrunken area 321b back to its
original size, i.e., that of the area 321a, during the course of image reading. The
expansion ratio can be determined by identifying the priority that was used. The image
processing apparatus 200 then decrypts the encrypted area 320a from the resized image
data.
[0150] The next section of this description will give a specific example of how markers
are placed when two encrypted areas 310a and 320a are closely located.
[0151] FIG. 16 is a second diagram illustrating how markers are placed according to the
second embodiment. Section (A) of FIG. 16 illustrates marker areas R1, R2, R3, and
R4 in the case where a designated area 320 is located on an encrypted area 310a. Section
(B) of FIG. 16 illustrates markers M1, M2, M3, and M4 placed in the respective marker
areas R1, R2, R3, and R4.
[0152] The marker area detection unit 140 detects marker areas R1, R2, R3, and R4 within
search areas Q1, Q2, Q3, and Q4 by removing their overlap with the encrypted area
310a. In the example seen in section (A), overlaps of search areas Q1 and Q2 with
the encrypted area 310a have been removed to produce marker areas R1 and R2. In contrast,
search areas Q3 and Q4 have no overlap with other encrypted areas. The resulting marker
areas R3 and R4 therefore coincide with the search areas Q3 and Q4.
[0153] The encryption unit 130 encrypts data in the designated area 320, thus producing
an encrypted area 320a.
[0154] The marking unit 150 places markers M1, M2, M3, and M4 at the highest-priority positions
in the respective marker areas R1, R2, R3, and R4 attached to the encrypted area 320a.
[0155] As can be seen from the above description, the image processing apparatus 100 places
markers M1 and M2 at appropriate positions along the boundary of an encrypted area
320a even though the encrypted area 320a is immediately adjacent to another encrypted
area 310a.
[0156] FIG. 17 is a third diagram illustrating how markers are placed according to the second
embodiment. Section (A) of FIG. 17 illustrates marker areas R1, R2, R3, and R4 in
the case where a designated area 320 is surrounded by an encrypted area 330a. Section
(B) of FIG. 17 illustrates markers M1, M2, M3, and M4 placed in the respective marker
areas R1, R2, R3, and R4.
[0157] The marker area detection unit 140 detects marker areas R1, R2, R3, and R4 within
search areas Q1, Q2, Q3, and Q4 by removing their overlap with the encrypted area
330a. As seen in section (A), marker areas R1, R2, R3, and R4 have no overlap with
the encrypted area 330a.
[0158] The encryption unit 130 encrypts data in the designated area 320, thus producing
an encrypted area 320a.
[0159] The marking unit 150 places markers M1, M2, M3, and M4 at the highest-priority position
in the respective marker areas R1, R2, R3, and R4 attached to the encrypted area 320a.
[0160] As can be seen from the above, the image processing apparatus 100 places markers
M1, M2, M3, and M4 at appropriate positions along the boundary of an encrypted area
320a even though the encrypted area 320a has a plurality of edges touching another
encrypted area 330a.
[0161] The markers M1, M2, M3, and M4 placed in this way permit the image processing apparatus
200 to decrypt data in the encrypted area 320a properly.
[0162] The next few sections of this description will now discuss how the image processing
apparatus 200 decrypts data.
[0163] FIG. 18 is a flowchart of a decryption process. Each step of this process is described
below in the order of step numbers.
[0164] (Step S41) The marker position detection unit 220 receives an encrypted image 300a.
[0165] (Step S42) The marker position detection unit 220 detects marker positions in the
received encrypted image 300a on the basis of shape and color pattern of markers,
with reference to decryption control data stored in the decryption control data storage
unit 210. For example, an area in the encrypted image 300a is detected as a marker
position when the area has a specific shape and color pattern that match with those
defined in the decryption control data.
[0166] (Step S43) The encrypted area detection unit 230 selects one set of markers (hereafter
"marker set"). Specifically, an encrypted area has markers at its four corners, each
having a distinct shape. The encrypted area detection unit 230 identifies these markers
as the marker set demarcating that encrypted area. When there are a plurality of marker
sets, they are selected in an appropriate order. For example, marker sets may be selected
in the order that their constituent markers are detected at step S42. For another
example, marker sets may be selected in ascending order of their coordinate values
(e.g., y-axis coordinates) in the encrypted image 300a.
[0167] (Step S44) The encrypted area detection unit 230 identifies an encrypted area based
on the selected marker set and outputs the identified encrypted area to the decryption
unit 240.
[0168] (Step S45) The decryption unit 240 decrypts the encrypted area received from the
encrypted area detection unit 230.
[0169] (Step S46) The decryption unit 240 determines whether there are any other pending
encrypted areas in the encrypted image 300a. When a pending area is found, the decryption
unit 240 goes back to step S43. When it is found that all encrypted areas are done,
the decryption unit 240 advances the process to step S47.
[0170] (Step S47) The decryption unit 240 has decrypted all encrypted areas in the encrypted
image 300a, and thus closes the present process after outputting the resulting decrypted
image 300b.
[0171] The above process identifies a marker set for each encrypted area in the encrypted
image 300a, and decrypts the encrypted area indicated by the marker set. When all
encrypted areas are decrypted, the resulting decrypted image 300b is output to, for
example, a monitor connected to the image processing apparatus 200.
[0172] The next section will provide details of step S44 described above. It is assumed
now that some reference markers are embedded in an encrypted area 320a selected out
of the encrypted image 300a.
[0173] FIG. 19 is a flowchart illustrating a process of identifying encrypted areas. Each
step of this process is described below in the order of step numbers.
[0174] (Step S51) The encrypted area detection unit 230 selects one marker out of the current
marker set in an appropriate order. For example, markers M1, M2, M3, and M4 are selected
in that order. Suppose here that the encrypted area detection unit 230 has selected
a marker M1, for example.
[0175] (Step S52) The encrypted area detection unit 230 detects the positions of reference
markers. For example, the encrypted area detection unit 230 obtains arrangement patterns
of reference markers M5, M6, M7, and M8 corresponding to the selected marker M1, by
consulting decryption control data stored in the decryption control data storage unit
210. More specifically, if observed markers match with one of those arrangement patterns,
then the encrypted area detection unit 230 takes them as reference markers M5, M6,
M7, M8 and thus detects their respective positions.
[0176] (Step S53) The encrypted area detection unit 230 investigates locational relationships
between the selected marker and each associated reference marker, thus determining
which priority was used to place the selected marker. The encrypted area detection
unit 230 achieves this by using the method discussed for determination of the priority
of marker M1 from reference markers M5, M6, M7, and M8 in FIG. 13.
[0177] (Step S54) Based on the priority of the selected marker, the encrypted area detection
unit 230 searches a priority table stored in the decryption control data storage unit
210, thereby determining a locational relationship between the selected marker and
encrypted area 320a. Based on the determined locational relationship, the encrypted
area detection unit 230 then determines the position of each corner point of the encrypted
area 320a which corresponds to the selected marker. Suppose, for example, that the
selected marker M1 has been determined to be of a priority of "2." In this case, the
designated area 320 learns from the priority table that the encrypted area 320a has
its corner point corresponding to marker M1 at the position that would be adjacent
to the inner corner of marker M1 if moved upward by half a block. The encrypted area
detection unit 230 gives a "finished" status to the selected marker.
[0178] (Step S55) The encrypted area detection unit 230 determines whether all markers in
the given marker set have undergone the above steps. If all markers are finished,
the encrypted area detection unit 230 advances the process to step S56. If there is
a pending marker, the encrypted area detection unit 230 goes back to step S51.
[0179] (Step S56) Now that the corner points of the encrypted area 320a are determined through
the above processing of steps S51 to S56, the encrypted area detection unit 230 informs
the decryption unit 240 of these corner points and then exits from the process.
[0180] In the way described above, the encrypted area detection unit 230 obtains information
indicating corner points of an encrypted area 320a and passes it to the decryption
unit 240.
[0181] The next section will describe a variation of the above described processing of step
S44. The above process of FIG. 19 assumes that reference markers are embedded in the
encrypted area 320a as seen in FIG. 13. In contrast, the following process assumes
that markers have different pixel patterns depending on their priorities as discussed
in FIG. 14. It is also assumed that an encrypted area 320a is currently selected from
among those in an encrypted image 300a.
[0182] FIG. 20 is a flowchart illustrating a variation of the above process of identifying
encrypted areas. FIG. 20 is different from FIG. 19 in that steps S52a and S53a are
executed instead of the foregoing steps S52 and S53. For the other steps, see the
above discussion in FIG. 19.
[0183] (Step S52a) The encrypted area detection unit 230 detects a color pattern of a marker.
For example, the encrypted area detection unit 230 detects that marker M1 is formed
from white and black pixels arranged in a specific pattern.
[0184] (Step S53a) With the detected pattern, the encrypted area detection unit 230 determines
which priority was used to place the marker in question. The encrypted area detection
unit 230 achieves this by using the method that was discussed previously in FIG. 14
for determination of the priority of marker M1.
[0185] The above procedure similarly permits the encrypted area detection unit 230 to obtain
information indicating corner points of an encrypted area 320a. The encrypted area
detection unit 230 passes the obtained information to the decryption unit 240.
[0186] Based on the information supplied from the encrypted area detection unit 230, the
decryption unit 240 determines boundaries of the encrypted area 320a and decrypts
data in that area.
[0187] The marker M1 may overlap with the encrypted area 320a. When this is the case, the
decryption unit 240 performs interpolation or extrapolation of pixel values to recover
the overlapped portion during the course of decryption.
[0188] The method of interpolation or extrapolation may depend on what algorithm the encryption
unit 130 and decryption unit 240 use for data protection. Specifically, the following
two methods are applicable.
[0189] First method: This method applies when the marker M1 overlaps with the area 321a
as seen in section (A) of FIG. 15, and if it is possible to decrypt the encrypted
area 320a without data in that overlapping area. The decryption unit 240 decrypts
the rest of the encrypted area 320a, individually for each divided area 321a, 322a,
323a, and 324a, or collectively for the entire encrypted area 320a. The decryption
unit 240 then interpolates or extrapolates the decrypted pixel values around marker
M1 to estimate the values of hidden pixels in the area of marker M1. In the case where
reference markers M5, M6, M7, and M8 are used, the decryption unit 240 executes interpolation
or extrapolation in the same way as it does for marker M1. For example, the method
proposed in Japanese Laid-open Patent Publication No.
2009-232233 may be used for the above interpolation or extrapolation.
[0190] Second method: This method applies when the area 321a is scaled down into an area
321b as discussed in section (B) of FIG. 15. The decryption unit 240 expands the area
321b back to its original size before decrypting the encrypted area 320a.
[0191] The encryption unit 130 may be configured to execute encryption without including
the area of marker M1. When this is the case, the encryption unit 130 determines an
encryption area by removing the area of marker M1, whose position is determined and
informed of by the marking unit 150. The above-noted first method of interpolation
and extrapolation also applies to this case. That is, the decryption unit 240 decrypts
pixels without including those of marker M1 and then interpolates or extrapolates
the decrypted pixel values around marker M1 to estimate the values of hidden pixels
in the area of marker M1.
[0192] The decryption unit 240 provides a decrypted image 300b in this way.
[0193] With the features described above, the image processing apparatus 100 places markers
at proper locations to demarcate encrypted areas 310a and 320a even in the case where
designated areas 310 and 320 are closely located. Specifically, the image processing
apparatus 100 is configured to detect marker areas for new markers before encrypting
a designated area 320. These marker areas do not overlap with an existing encrypted
area 310a and its associated markers. The image processing apparatus 100 then determines
where to place markers in the detected marker areas according to predetermined priority
conditions.
[0194] The above markers permit another image processing apparatus 200 to locate the encrypted
areas 310a and 320a correctly, in spite of their close proximity. Each encrypted area
can therefore be deciphered in a proper way.
[0195] The proposed features contribute to a higher degree of freedom in the layout of a
plurality of encrypted areas. More particularly, it is possible to lay out encrypted
areas at closer locations than the conventional apparatuses can do.
[0196] The above-described marker placement method may similarly be used to print a plurality
of two-dimensional codes on a single medium. The proposed method reduces the space
for two-dimensional codes because of its ability to lay out such codes at closer locations.
[0197] The shape of markers is not limited by the examples discussed in the present embodiment.
Rather, markers may have a variety of shapes as will be described below.
[0198] FIG. 21 illustrates a first variation of markers and marker areas. Section (A) of
FIG. 21 illustrates an option for the shape and pixel pattern of markers. Section
(B) of FIG. 21 illustrates search areas for such markers.
[0199] Markers M1a, M2a, M3a, and M4a are placed in the vicinity of four corners of an encrypted
area 320a. These markers M1a, M2a, M3a, and M4a have a particular pixel pattern that
is formed from a black circle and a black cross "x" in that circle. This pattern may
further be modified by changing, for example, the thickness of the black circle. Other
modifications may change the ratio of thickness between two black lines constituting
the cross, or alter the crossing angle of these two lines. The resulting variations
add more options to the pixel pattern of markers.
[0200] The image processing apparatus 100 may use such markers M1a, M2a, M3a, and M4a in
place of the foregoing markers M1, M2, M3, and M4.
[0201] The image processing apparatus 200 determines the boundaries of the encrypted area
320a by detecting those markers M1a, M2a, M3a, and M4a.
[0202] Search areas Q1a, Q2a, Q3a, and Q4a are potential locations of markers M1a, M2a,
M3a, and M4a around a designated area 320. The control data storage unit 110 stores
control data that defines such search areas Q1a, Q2a, Q3a, and Q4a containing four
corners of the designated area 320.
[0203] The marker area detection unit 140 may be configured to minimize the search areas
Q1a, Q2a, Q3a, and Q4a, depending on the shape of markers M1a, M2a, M3a, and M4a.
By so doing, the marker area detection unit 140 reduces the time for detecting marker
areas.
[0204] FIG. 22 illustrates a second variation of markers and marker areas. Section (A) of
FIG. 22 illustrates another option for the shape and pixel pattern of markers. Section
(B) of FIG. 22 illustrates search areas for such markers.
[0205] Markers M1b, M2b, M3b, and M4b are placed at four corners of an encrypted area 320a.
These markers M1b, M2b, M3b, and M4b have a particular pixel pattern that is formed
from a black rectangular frame and a black solid box in that frame. This pattern may
further be modified by changing, for example, the proportion of the inner black box
to the outer black frame. The resulting variations add more options to the pixel pattern
of markers.
[0206] Search areas Q1b, Q2b, Q3b, and Q4b are potential locations of markers M1b, M2b,
M3b, and M4b around a designated area 320. The control data storage unit 110 stores
control data that defines such search areas Q1b, Q2b, Q3b, and Q4b containing four
corners of the designated area 320.
[0207] Priority tables are also prepared in the control data storage unit 110 when the image
processing apparatus 100 uses the markers illustrated in FIGS. 21 and 22. Using this
control data storage unit 110, the image processing apparatuses 100 and 200 perform
their processing operations similar to what they do for the foregoing markers M1,
M2, M3, and M4. Accordingly, the image processing apparatuses 100 and 200 achieve
the same effects as they do with the foregoing markers M1, M2, M3, and M4. The markers
illustrated in FIGS. 21 and 22 also have different priorities depending on their relative
locations with respect to the designated area. For example, a lower priority is given
to markers when their location is closer to the designated area. Further, a lower
priority is given to markers when their location is closer to the center of the designated
area.
[Third Embodiment]
[0208] This section describes a third embodiment with reference to the accompanying drawings.
The description of the third embodiment will focus on its difference from the foregoing
second embodiment. See the previous sections for their common features.
[0209] In the second embodiment described above, there are two areas 310a and 320a encrypted
in that order. The marker positions for the latter encrypted area 320a have thus to
be adjusted with consideration of the existing encrypted area 310a. However, a designated
area 320 for the latter encrypted area 320a may overlap with an existing marker of
the former encrypted area 310a. If this is the case, it is not always possible to
place new markers.
[0210] The third embodiment deals with the above case by trying to place markers for the
new encrypted area 320a while adjusting the existing marker of the encrypted area
310a. The following description is directed to an image processing apparatus designed
to perform such adjustment of existing markers.
[0211] The third embodiment is intended for use in the same information processing system
whose overall structure has been discussed in the second embodiment with reference
to FIG. 2. See the previous description for details of the system structure. The information
processing system of the third embodiment, however, includes an image processing apparatus
100a in place of the image processing apparatus 100 in FIG. 2. This image processing
apparatus 100a has the same hardware configuration as the one discussed for the image
processing apparatus 100 in FIG. 3. See the previous description for details of the
hardware configuration.
[0212] FIG. 23 illustrates a structure of an image processing apparatus according to the
third embodiment. The illustrated image processing apparatus 100a includes a control
data storage unit 110, an encryption area designation unit 120, an encryption unit
130, a marker area detection unit 140, a marking unit 150, and an adjoining marker
changing unit 160. These functions are realized as programs executed by the CPU 101.
Alternatively, all or part of these functions may be implemented as a dedicated hardware
device(s).
[0213] The control data storage unit 110, encryption area designation unit 120, encryption
unit 130, marker area detection unit 140, and marking unit 150 are equivalent to their
respective counterparts in the foregoing image processing apparatus 100 of FIG. 4,
with the same names and reference numerals. For the details of these elements, see
relevant part of the previous description.
[0214] It is noted, however, that the encryption area designation unit 120 is modified to
supply information about designated areas also to the adjoining marker changing unit
160.
[0215] Each existing encrypted area is marked with a set of markers for the purpose of distinction
from other areas. Some of these markers may overlap with a designated area designated
by the encryption area designation unit 120. The adjoining marker changing unit 160
changes the positions of such markers (hereafter referred to as "adjoining markers").
More specifically, the adjoining marker changing unit 160 moves adjoining markers
to other positions with a lower priority by manipulating data of the input image 300
with reference to a relevant priority table 111 stored in the control data storage
unit 110.
[0216] When an adjoining marker(s) is found in the input image 300, the marker area detection
unit 140 detects marker areas based on the input image 300 modified by the adjoining
marker changing unit 160.
[0217] As will be seen in the following description, the markers M1, M2, M3, and M4 in the
second embodiment are also used in the fourth embodiment. It is possible, however,
to use other markers with different shapes (e.g., those discussed in FIGS. 21 and
22).
[0218] The following section provides details of processing operation executed by the above
image processing apparatus 100a.
[0219] FIG. 24 is a flowchart illustrating an encryption process according to the third
embodiment. Each step of this process is described below in the order of step numbers.
[0220] (Step S62) The encryption area designation unit 120 receives an input image 300.
[0221] (Step S62) The encryption area designation unit 120 permits the user to designate
a specific area(s) in the input image 300. It is assumed now that the user has designated
two or more areas.
[0222] (Step S63) The encryption area designation unit 120 selects one of the designated
areas. The order of this selection may be determined in the same way as in step S13
of FIG. 9. Suppose, for example, that there are two designated areas 310 and 320.
The encryption area designation unit 120 selects the former area 310 in the first
place and informs the encryption unit 130, marker area detection unit 140, and adjoining
marker changing unit 160 of the selected area.
[0223] (Step S64) The encryption unit 130 encrypts the designated area in the input image
300 that is informed of by the encryption area designation unit 120. The encryption
unit 130 produces and stores control data in the control data storage unit 110 to
record which part of the input image 300 is encrypted. For example, this control data
may indicate the corner points of the encrypted area.
[0224] (Step S65) The adjoining marker changing unit 160 detects adjoining markers and changes
their locations.
[0225] (Step S66) With reference to control data stored in the control data storage unit
110, the marker area detection unit 140 obtains search areas Q1, Q2, Q3, and Q4 relevant
to the designated area informed of by the encryption area designation unit 120. Out
of these search areas Q1, Q2, Q3, and Q4, the marker area detection unit 140 detects
appropriate marker areas by excluding coordinate points that overlap with other encrypted
areas or their associated markers. The marker area detection unit 140 provides the
marking unit 150 with the detected marker areas.
[0226] (Step S67) With reference to a relevant priority table 111 stored in the control
data storage unit 110, the marking unit 150 places a marker at the highest-priority
position in each marker area so as to indicate the encrypted area in the input image
300. The marking unit 150 adds control data to the control data storage unit 110 to
record the marked areas (e.g., record the corner positions of each area).
[0227] (Step S68) The marking unit 150 determines whether there is any other pending designated
area in the input image 300. If there is, the marking unit 150 advances the process
to step S63. If all the designated area are finished, the marking unit 150 outputs
the resulting encrypted image 300a, thus terminating the present process.
[0228] As can be seen from the above steps, the image processing apparatus 100 encrypts
data locally in each designated area. During this course, the image processing apparatus
100 seeks adjoining markers and changes their positions.
[0229] The above process executes encryption at step S64. Alternatively, the flowchart may
be modified to perform the same immediately before the marker placement of step S67.
[0230] The next section will provide more details of step S65 described above.
[0231] FIG. 25 is a flowchart illustrating how adjoining markers are changed according to
the third embodiment. Each step of this process is described below in the order of
step numbers.
[0232] (Step S71) The adjoining marker changing unit 160 determines whether any existing
markers overlap with the designated area designated by the encryption area designation
unit 120. When such overlap is found, the adjoining marker changing unit 160 advances
the process to step S72. When no such overlap is found, the adjoining marker changing
unit 160 exits from the present process.
[0233] (Step S72) The adjoining marker changing unit 160 selects an adjoining marker, i.e.,
one of those overlapping markers. The adjoining marker changing unit 160 then determines
which priority was used to place the selected adjoining marker. The priority of adjoining
markers may be determined in the same way discussed above in FIGS. 19 and 20. Alternatively,
the priority of adjoining markers may be recorded in the control data storage unit
110 when they are placed, so that the adjoining marker changing unit 160 can consult
the record later to determine the priority. As another alternative, the priority of
adjoining markers may be recorded in the header of the image data when they are placed,
so that the adjoining marker changing unit 160 can consult the header information
later to determine the priority.
[0234] (Step S73) The adjoining marker changing unit 160 deletes the selected adjoining
marker. The adjoining marker changing unit 160 fills the vacated area by using interpolation
or extrapolation techniques. More specifically, the adjoining marker changing unit
160 may use the method described in Japanese Laid-open Patent Publication No.
2009-232233. For example, pixel values may be estimated from image data in the surrounding areas.
Alternatively, the deleted area may be recovered from a partial original image that
was previously saved.
[0235] (Step S74) The adjoining marker changing unit 160 selects a priority that is lower
than the priority determined at step S72 for the now-deleted adjoining marker. For
example, the adjoining marker changing unit 160 may select a priority that is one
rank lower than the priority of step S72. The adjoining marker changing unit 160 then
consults a relevant priority table 111 in the control data storage unit 110 to find
a marker position with the selected priority.
[0236] (Step S75) The adjoining marker changing unit 160 places a marker at the determined
marker position as an alternative to the deleted adjoining marker. The adjoining marker
changing unit 160 then return to step S71.
[0237] The above process changes the positions of adjoining markers one by one until no
overlap of markers with the designated area is observed.
[0238] FIGS. 26 and 27 provide some examples illustrating how markers are placed according
to the third embodiment.
[0239] The encryption area designation unit 120 receives input of designated areas 310 and
320 in an input image 300. Both designated areas 310 and 320 are box-shaped, and one
designated area 310 is in contact with another designated are 320 at one of their
corner points. The encryption area designation unit 120 first selects the former designated
area 310 out of the two. The encryption unit 130 produces an encrypted area 310a from
the designated area 310, and the marking unit 150 adds markers to the encrypted area
310a.
[0240] The encryption area designation unit 120 then selects the other designated area 320.
[0241] The adjoining marker changing unit 160 now detects an adjoining marker MA1 as one
of the markers added to the encrypted area 310a. The adjoining marker changing unit
160 then determines which priority was used to place this adjoining marker MA1. For
example, the adjoining marker changing unit 160 finds the priority to be "1" (step
ST1).
[0242] The adjoining marker changing unit 160 deletes the adjoining marker MA1 and fills
the vacated area by using appropriate techniques (step ST2).
[0243] There may have been several positions suitable for the adjoining marker MA1. The
adjoining marker changing unit 160 selects a position with a lower priority from among
those positions and places an alternative marker at that position. For example, the
adjoining marker changing unit 160 places a marker at a position with a priority of
"2," which is one rank lower than the original priority of "1." The adjoining marker
changing unit 160 moves the marker until it reaches a position having no overlap with
the designated area 320, by successively lowering the priority (i.e., by repeating
steps ST1 and ST2). Finally the adjoining marker changing unit 160 places a marker
MA1a at the position with a priority of "4," for example. This position of the new
marker MAla resolves the overlap with the designated area 320. The adjoining marker
changing unit 160 thus finishes the process of changing adjoining markers (step ST3).
[0244] Based of the image data including adjoining markers modified above by the adjoining
marker changing unit 160, the marker area detection unit 140 detects search areas
for the designated area 320 that the encryption unit 130 has encrypted. The marking
unit 150 places a marker at the highest-priority position within each search area
that the marker area detection unit 140 has detected. As a result of this operation,
a marker MB1 is added to the position next to the corner of marker MAla. For example,
the position of this marker MB1 is of a priority of "4," which is selected to avoid
overlap with the marker MA1a.
[0245] As can be seen from the above, the proposed image processing apparatus 100a is designed
to add markers to a designated area after moving an adjoining marker, if any, to another
place that resolves the overlap with the designated area. This feature of the image
processing apparatus 100a enables proper placement of markers for a designated area
even in the case where some existing markers overlap with the designated area.
[0246] The above-described processing of the third embodiment enhances the degree of freedom
in laying out a plurality of encrypted areas, when compared with the foregoing second
embodiment. This means that the encrypted areas can be located more closely. The third
embodiment thus contributes to more space-efficient layout of encrypted areas.
[Fourth Embodiment]
[0247] This section describes a fourth embodiment with reference to the accompanying drawings.
The description of the fourth embodiment will focus on its difference from the foregoing
second and third embodiments. See the previous sections for their common features.
[0248] The foregoing second and third embodiments seek an appropriate position for a new
marker to avoid its overlap with other existing markers. However, it may also be possible
to use a portion of an existing marker as part of a new marker, under some specific
conditions of the shape of markers used or locational relationships between markers.
The fourth embodiment provides an image processing apparatus that enables such partial
sharing of markers.
[0249] The fourth embodiment is intended for use in the same information processing system
whose overall structure has been discussed in the second embodiment with reference
to FIG. 2. See the previous description for details of the system structure. The information
processing system of the fourth embodiment, however, includes an image processing
apparatus 100b in place of the image processing apparatus 100 in FIG. 2. This image
processing apparatus 100b has the same hardware configuration as the one discussed
in FIG. 3 for the image processing apparatus 100. See the previous description for
details of the hardware configuration.
[0250] The following description assumes that the foregoing markers M1, M2, M3, and M4 in
the second embodiment are used also in the fourth embodiment.
[0251] FIG. 28 illustrates a structure of an image processing apparatus according to the
fourth embodiment. The illustrated image processing apparatus 100b includes a control
data storage unit 110, an encryption area designation unit 120, an encryption unit
130, a marker area detection unit 140, a marking unit 150, and a combination coordinate
point determination unit 170. These functions are realized as programs executed by
the CPU 101. Alternatively, all or part of these functions may be implemented as a
dedicated hardware device(s).
[0252] The control data storage unit 110, encryption area designation unit 120, encryption
unit 130, marker area detection unit 140, and marking unit 150 are equivalent to their
respective counterparts in the foregoing image processing apparatus 100 of FIG. 4,
with the same names and reference numerals. For the details of these elements, see
the previous description.
[0253] With reference to the control data storage unit 110, the combination coordinate point
determination unit 170 determines a combination coordinate point based on the positions
of a search area and existing markers in the input image 300. The term "combination
coordinate point" refers to the coordinates representing a point at which an additional
marker with a different shape is to be placed in combination with one of the existing
markers M1, M2, M3, and M4. Specifically, markers M1, M2, M3, and M4 are in the shape
of letter "L" and composed of two bars that join at one end. The noted additional
marker may be placed at that end point (described later). The combination coordinate
point determination unit 170 informs the marking unit 150 of the determined combination
coordinate point.
[0254] When it has combination coordinate point provided from the combination coordinate
point determination unit 170, the marking unit 150 uses that coordinate point to place
a marker in preference to other potential marker positions. When it has no such combination
coordinate point, the marking unit 150 consults a relevant priority table 111 in the
control data storage unit 110 to find marker positions within a marker area provided
from the marker area detection unit 140. The marking unit 150 then places a marker
at the highest-priority position in the marker area.
[0255] The following section provides details of processing operation executed by the above
image processing apparatus 100b.
[0256] FIG. 29 illustrates some markers used for combining operation of the fourth embodiment.
Section (A) of FIG. 29 illustrates a joining position. Section (B) of FIG. 29 illustrates
an example of additive markers. Section (C) of FIG. 29 illustrates another example
of additive markers. FIG. 29 illustrates an L-shaped maker M3 having a joining position
BL1 at which the horizontal pixel pattern of marker M3 meets the vertical pixel pattern
of the same. The combination coordinate point in this case represents the center of
this joining position BL1.
[0257] Additive markers M11 and M12 are defined as additional markers that may be placed
at the joining position BL1 of markers M1, M2, M3, and M4.
[0258] One additive marker M11 has two joining positions BL2 and BL3. For example, the marker
M3 may be combined with this additive marker M11 by overlaying the latter on the former
in such a way that their joining positions BL1 and BL2 are aligned with each other.
[0259] The other additive marker M12 also has two joining positions BL4 and BL5. For example,
the marker M3 may be combined with this additive marker M12 by overlaying the latter
on the former in such a way that their joining positions BL1 and BL4 are aligned with
each other.
[0260] It is noted that these additive markers M11 and M12 are placed only when they fit
in a search area in their respective entireties.
[0261] FIG. 30 illustrates a locational relationship between an existing marker and a search
area according to the fourth embodiment. The illustrated marker MC1 is one of those
added to an existing encrypted area. The illustrated search area Q1 is formed from
a top portion Qt and a left portion Q1. The top portion Qt and left portion Q1 partly
overlap with each other. This overlapping area belongs to both the top portion Qt
and left portion Q1.
[0262] As FIG. 30 illustrates, the horizontal bar of the existing marker MC1 lies within
the top portion Qt of the search area Q1. This kind of state of markers may be expressed
as "one element of the existing marker is wholly within the search area," as will
be seen below.
[0263] Other search areas Q2, Q3, and Q4 may also be divided into constituent portions similarly
to the above. For example, search area Q2 is divided into a top portion and a right
portion. Search area Q3 is divided into a bottom portion and a left portion. Search
area Q4 is divided into a bottom portion and a right portion.
[0264] The following section provides details of processing operation executed by the above
image processing apparatus 100b.
[0265] FIG. 31 is a flowchart illustrating an encryption process according to the fourth
embodiment. Each step of this process is described below in the order of step numbers.
[0266] (Step S81) The encryption area designation unit 120 receives an input image 300.
[0267] (Step S82) The encryption area designation unit 120 permits the user to designate
a specific area(s) in the input image 300. It is assumed now that the user has designated
two or more areas.
[0268] (Step S83) The encryption area designation unit 120 selects one of the designated
areas. The order of this selection may be determined in the same way as in step S13
of FIG. 9. Suppose, for example, that there are two designated areas 310 and 320.
The encryption area designation unit 120 selects the former area 310 in the first
place and informs the encryption unit 130 and marker area detection unit 140 of the
selected area.
[0269] (Step S84) The encryption unit 130 encrypts the designated area in the input image
300 that is informed of by the encryption area designation unit 120. The encryption
unit 130 produces and stores control data in the control data storage unit 110 to
record which part of the input image 300 is encrypted. For example, this control data
may indicate the corner points of the encrypted area.
[0270] (Step S85) With reference to control data stored in the control data storage unit
110, the marker area detection unit 140 obtains search areas Q1, Q2, Q3, and Q4 relevant
to the designated area informed of by the encryption area designation unit 120. Out
of these search areas Q1, Q2, Q3, and Q4, the marker area detection unit 140 detects
appropriate marker areas by excluding coordinate points that overlap with other encrypted
areas or their associated markers. The marker area detection unit 140 provides the
marking unit 150 and combination coordinate point determination unit 170 with the
detected marker areas.
[0271] (Step S86) The combination coordinate point determination unit 170 determines whether
the selected search area overlaps with existing markers. If such overlap is found,
the combination coordinate point determination unit 170 advances the process to step
S87. If no such overlap is found, the combination coordinate point determination unit
170 advances the process to step S88. The word "overlap" is used here to mean that
one element of an existing marker is wholly within the search area. If, for example,
the foregoing existing marker MC1 does not satisfy this condition with respect to
the search area Q1, combining an additive marker to the existing marker MC1 would
not work well for the currently selected designated area. This is because the resulting
marker would not have a proper shape or proper pixel pattern. For example, the combined
marker could have a width of five blocks and a height of three blocks, whereas all
markers are supposed to have dimensions of five by five blocks. For this reason, the
combination coordinate point determination unit 170 is configured to combine markers
only when one element of an existing marker is wholly within the search area.
[0272] (Step S87) The combination coordinate point determination unit 170 tries to combine
an additive marker with the existing marker. When this works out properly, the combination
coordinate point determination unit 170 obtains and supplies a combination coordinate
point to the marking unit 150. When the combination does not work, the combination
coordinate point determination unit 170 sends nothing to the marking unit 150.
[0273] (Step S88) When a combination coordinate point is received, the marking unit 150
places an additive marker at that coordinate point. When no combination coordinate
point is received, the marking unit 150 consults a relevant priority table 111 in
the control data storage unit 110 to find marker positions within a marker area provided
from the marker area detection unit 140. The marking unit 150 then places a marker
at the highest-priority position in the marker area. The marking unit 150 adds control
data to the control data storage unit 110 to record the marked areas (e.g., record
the corner positions of each area).
[0274] (Step S89) The marking unit 150 determines whether there is any pending designated
area in the input image 300. If there is, the marking unit 150 advances the process
to step S83. If all the designated area are finished, the marking unit 150 outputs
the resulting encrypted image 300a, thus terminating the present process.
[0275] As can be seen from the above, a combination coordinate point is determined when
there is an overlap between a search area and an existing marker. In this case, an
additive marker is placed at the determined combination coordinate point in preference
to normal markers.
[0276] The above process executes encryption at step S84. Alternatively, the flowchart may
be modified to perform the same immediately before the marker placement of step S88.
[0277] The next section will provide details of step S87 described above.
[0278] FIG. 32 is a flowchart illustrating a process of determining marker combination coordinates
according to the fourth embodiment. Each step of this process is described below in
the order of step numbers.
[0279] (Step S91) The combination coordinate point determination unit 170 selects one coordinate
point from among those in an overlapping area of the search area with an existing
marker.
[0280] (Step S92) The combination coordinate point determination unit 170 tries to place
an additive marker at the selected coordinate point. The shape of this additive marker
may vary, depending upon in which part of the designated area the marker area in question
resides, and also upon in which part of the marker area the existing marker in question
resides. Suppose, for example, that the search area Q1 overlaps with one element of
an existing marker. Additive marker M11 is then selected when the overlap lies in
the top portion Qt of the search area Q1. Additive marker M12 is selected when the
overlap lies in the left portion Q1 of the search area Q1.
[0281] The combination coordinate point determination unit 170 now determines whether the
additive marker, if placed at the selected coordinate point, would affect the pixel
pattern of the existing marker. If no changes are expected, the combination coordinate
point determination unit 170 advances the process to step S93. If the existing marker
pattern is expected to "change," the combination coordinate point determination unit
170 advances the process to step S95. The word "change" is used here to mean, for
example, that the marker's original color pattern (e.g., black-white-black-while-black)
is affected by an additive marker and thus makes a different pattern (e.g., black-black-black-while-black,
or black-white-black-black-black). Moreover, when the selected coordinate point is
not the center of a block of the existing marker, the color of that block could be
disturbed by an additive marker (i.e., white pixels could be introduced into a black
block, and vice versa).
[0282] (Step S93) The combination coordinate point determination unit 170 determines whether
the additive marker in question is placeable in the search area. When it is placeable,
the combination coordinate point determination unit 170 advances the process to step
S94. When it is not placeable, the combination coordinate point determination unit
170 advances the process to step S95.
[0283] (Step S94) The combination coordinate point determination unit 170 outputs the coordinate
point selected at step S91, thus providing it to the marking unit 150 as a combination
coordinate point. The combination coordinate point determination unit 170 then exits
from the present process.
[0284] (Step S95) The combination coordinate point determination unit 170 determines whether
all the overlapping coordinate points are finished. If a pending coordinate point
is found, the combination coordinate point determination unit 170 advances the process
back to step S91. If all the coordinate points are done, the combination coordinate
point determination unit 170 exits from the present process.
[0285] The above process determines a combination coordinate point for placement of an additive
marker. This determination is made by testing whether the additive marker would affect
the pixel pattern of an existing marker if it was placed at each particular coordinate
point in an overlapping area of the search area and existing marker.
[0286] The next section will describe a more specific example of marker placement performed
by the marking unit 150.
[0287] FIG. 33 illustrates how markers are placed according to the fourth embodiment. Section
(A) of FIG. 33 illustrates the case where an encrypted area 310a is located in the
vicinity of a designated area 320, and the horizontal bar of an existing marker MC1
is wholly contained in a search area Q1 of the designated area 320. The designated
area 320 is then encrypted. Section (B) of FIG. 33 illustrates markers added to the
resulting encrypted area 320a.
[0288] The combination coordinate point determination unit 170 recognizes that the horizontal
bar of an existing marker MC1 is wholly contained in a search area Q1 of the designated
area 320. Accordingly, the combination coordinate point determination unit 170 tries
to place an additive marker at a coordinate point in the overlapping area of the existing
marker MC1 and search area Q1. An additive marker M11 is chosen for the purpose since
the overlap is in the top portion Qt of the search area Q1. The combination coordinate
point determination unit 170 then seeks a position that permits an additive marker
M11 to be wholly contained in the search area Q1 without changing the pixel pattern
of the existing marker MC1. For example, the combination coordinate point determination
unit 170 selects the center of joining position BL1 of the existing marker MC1. The
combination coordinate point determination unit 170 then provides the marking unit
150 with the center coordinates as a combination coordinate point.
[0289] The marking unit 150 places an additive marker M11 at the combination coordinate
point determined by the combination coordinate point determination unit 170, thereby
producing a combined marker MC1a.
[0290] This combined marker MC1a may be used to identify a corner point, not only of one
encrypted area 310a, but also of another encrypted area 320a. The image processing
apparatus 200 properly locates these encrypted areas 310a and 320a by detecting their
respective markers including the combined marker MC1a.
[0291] As can be seen from the above, the proposed image processing apparatus 100b is configured
to produce a combined marker MC1a by adding an additive marker M11 to an existing
marker MC1 under some specific conditions. This feature contributes to reduction of
overlaps of encrypted areas 310a and 320a with each other's markers. In other words,
only a smaller portion of the encrypted areas 310a and 320a needs interpolation or
extrapolation, thus improving efficiency of data decryption at the reading end.
[0292] The next section will describe a variation of the above described process of determining
marker combination coordinates.
[0293] FIG. 34 is a flowchart illustrating a variation of the encryption process according
to the fourth embodiment. Each step of this process is described below in the order
of step numbers.
[0294] (Step S101) The encryption area designation unit 120 receives an input image 300.
[0295] (Step S102) The encryption area designation unit 120 permits the user to designate
a specific area(s) in the input image 300. It is assumed now that the user has designated
two or more areas.
[0296] (Step S103) The encryption area designation unit 120 selects one of the designated
areas. The order of this selection may be determined in the same way as in step S13
of FIG. 9. Suppose, for example, that there are two designated areas 310 and 320.
The encryption area designation unit 120 selects the former area 310 in the first
place and informs the encryption unit 130 and marker area detection unit 140 of the
selected area.
[0297] (Step S104) With reference to control data stored in the control data storage unit
110, the marker area detection unit 140 obtains search areas Q1, Q2, Q3, and Q4 relevant
to the designated area informed of by the encryption area designation unit 120. Out
of these search areas Q1, Q2, Q3, and Q4, the marker area detection unit 140 detects
appropriate marker areas by excluding coordinate points that overlap with other encrypted
areas or their associated markers. The marker area detection unit 140 provides the
marking unit 150 and combination coordinate point determination unit 170 with the
detected marker areas.
[0298] (Step S105) The combination coordinate point determination unit 170 determines whether
any search area overlap with an existing marker. When an overlap is found, the combination
coordinate point determination unit 170 advances the process to step S108. If no overlap
is found, the combination coordinate point determination unit 170 advances the process
to step S106. This determination of overlaps is achieved by using the foregoing method
of step S86 in FIG. 31.
[0299] (Step S106) The combination coordinate point determination unit 170 determines whether
it is possible to produce an overlap relationship between a search area and an existing
marker by modifying the designated area. If it is found to be possible, the combination
coordinate point determination unit 170 advances the process to step S107. If it is
found to be not possible, the combination coordinate point determination unit 170
advances the process to step S109. Here the term "overlap relationship" refers to
a particular state of locational relationships between a search area and an existing
marker that can be recognized as an overlap at step S105. More specifically, it means
that one element of the existing marker is wholly contained in the search area.
[0300] (Step S107) The combination coordinate point determination unit 170 modifies the
designated area. For example, the combination coordinate point determination unit
170 expands the designated area in a particular direction (e.g., leftward, rightward,
upward, or downward) until the aforementioned overlap relationship is established.
Another possible modification may be to move the designated area up to a point at
which the aforementioned overlap relationship is established. The combination coordinate
point determination unit 170 informs the encryption unit 130 of the modified range
of the designated area, and then advances the process to step S108.
[0301] (Step S108) The combination coordinate point determination unit 170 tries to combine
an additive marker with the existing marker. When this works out properly, the combination
coordinate point determination unit 170 obtains and supplies a combination coordinate
point to the marking unit 150. When the combination does not work, the combination
coordinate point determination unit 170 sends nothing to the marking unit 150.
[0302] (Step S109) The encryption unit 130 may have received information about a modified
version of the designated area from the combination coordinate point determination
unit 170 at step S107. When this is the case, the encryption unit 130 encrypts the
modified designated area in the input image 300. When that is not the case, the encryption
unit 130 encrypts the original designated area provided from the encryption area designation
unit 120. The encryption unit 130 produces and stores control data in the control
data storage unit 110 to record which part of the input image 300 is encrypted. For
example, this control data may indicate the corner points of the encrypted area.
[0303] (Step S110) The marking unit 150 may have previously received a combination coordinate
point from the combination coordinate point determination unit 170. When this is the
case, the marking unit 150 places an additive marker at that combination coordinate
point. When that is not the case, the marking unit 150 consults a relevant priority
table 111 in the control data storage unit 110 to find marker positions within a marker
area provided from the marker area detection unit 140. The marking unit 150 then places
a marker at the highest-priority position in the marker area. The marking unit 150
adds control data to the control data storage unit 110 to record the marked areas
(e.g., record the corner positions of each area).
[0304] (Step S111) The marking unit 150 determines whether there is any pending designated
area in the input image 300. If there is, the marking unit 150 advances the process
to step S103. If all the designated area are finished, the marking unit 150 outputs
the resulting encrypted image 300a, thus terminating the present process.
[0305] As can be seen from the above flowchart, the designated area is modified in the case
where step S106 finds no established "overlap relationships." In this case, a combined
marker is produced after an "overlap relationship" is produced.
[0306] The next section will describe a more specific example of marker placement performed
by the marking unit 150 in the present variation.
[0307] FIG. 35 illustrates a variation of the marking process according to the fourth embodiment.
Section (A) of FIG. 35 illustrates the case where an encrypted area 310a is located
in the vicinity of a designated area 320, and the horizontal bar MC1h of an existing
marker MC1 is wholly contained in a search area Q1 of the designated area 320. It
is assumed here that the above horizontal bar MC1h is located with a gap of L1 from
the search area Q1. The designated area 320 is then encrypted. Section (B) of FIG.
35 illustrates markers added to the resulting encrypted area 320a.
[0308] The combination coordinate point determination unit 170 finds it possible to make
the search area Q1 contain the horizontal bar MC1h in its entirety by expanding the
designated area 320 by a length of L2 in the leftward direction. The combination coordinate
point determination unit 170 then executes this expansion of the designated area 320.
The combination coordinate point determination unit 170 informs the encryption unit
130 of the new range of the designated area. It is noted that, as an alternative to
the expansion, the combination coordinate point determination unit 170 may move the
designated area 320 leftward by a distance of L2.
[0309] The subsequent processing of the image processing apparatus 100b is basically similar
to what have already been described in FIGS. 32 and 33. One difference is that the
encryption unit 130 applies data encryption to the modified designated area to produce
an encrypted area 320a. Another difference is that the marking unit 150 combines an
additive marker M11 with the existing marker MC1, thereby producing a combined marker
MC1a.
[0310] The above-described variation of the proposed method enables the image processing
apparatus 100b to produce a combined marker MC1a by adding an additive marker M11
to an existing marker MC1. This feature increases the chance of creating a combined
marker MC1a and thus contributes to reduction of overlaps of encrypted areas 310a
and 320a with each other's markers. In other words, only a smaller portion of the
encrypted areas 310a and 320a needs interpolation or extrapolation, thus improving
efficiency of data decryption at the reading end.
[0311] The above sections have exemplified several embodiments of the proposed image processing
apparatus and image processing method. It is not intended, however, to limit the embodiments
by those examples. For example, the described components may be replaced with other
components having equivalent functions. In addition, the embodiments may include other
components or processing operations. Where appropriate, two or more components and
features provided in the foregoing embodiments may be combined in a different way.
[0312] The foregoing is considered as illustrative only of the principles of the present
invention. Further, since numerous modifications and changes will readily occur to
those skilled in the art, it is not desired to limit the invention to the exact construction
and applications shown and described, and accordingly, all suitable modifications
and equivalents may be regarded as falling within the scope of the invention in the
appended claims and their equivalents.
Reference Signs List
[0313]
1: image processing apparatus
1a: area designation unit
1b: image processing unit
1c: marker area detection unit
1d: marking unit
2: input image
3: output image
4: processing area
5: marker area
6: marker